Leveling and stabilizing apparatus



May 7, 1963 W. E- STILWELL, JR

LEVELING AND STABILIZING APPARATUS 5 Sheets-Sheet 1 Filed March 2, 1959INVENTOR. WILLIAM E STILWELL JR ATTORNEY y 1963 w. E. STILWELL, JR3,088,593

LEVELING AND STABILIZINGY APPARATUS Filed March 2, 1959 I r 5Sheets-Sheet 2 WlLLIAM E, STILWELLJR.

WNW

ATTORNEY y 7, 1963 w. STILWELL, JR 3,088,593

LEVELING AND STABILIZING APPARATUS Filed March 2, 1959 5 Sheets-Sheet 8Zlg 21s INVENTOR. WILLIAM. E. STI U..WELL JR.

AT TO RNEY y 1963 w. E. STILWELL, JR 3,088,593

LEVELING AND STABILIZING APPARATUS 5 Sheets-Sheet 5 Filed Marcbh 2 1959INVENTOR. WlLLlAM E .STILWE LL,.JR.

ATTORNEY United States This invention relates to combination levellingand stabilizing apparatus for laundry appliances, and also to theutilization of such apparatus for sensing unbalanced rotational forcesand for de-activating the prime mover in response to such forceswhenever they become intolerable.

Laundry appliances, particularly of the tumble wash, centrifugalextraction, vibration isolation type, are normally required to beinstalled level, irrespective of floor irregularities, and stable,irrespective of the proper distribution of the weight of the machineupon its supporting feet. To achieve both a level and a stableinstallation, the practice has been to provide individually, manually,vertically adjustable feet at the four corners of the machine.

Two difficulties arise in such installations, since a machine can belevel without being stable and stable without being level. To achievetwo directional levelness, despite uneven and unlevel flooring, the two,rarely accessible, rear feet and the two, generally accessible, frontfeet must be properly adjusted. To establish stability, only one footneed be .adjusted, but the extreme care and fineness required in makingthe adjustment is such as to make real stability diificult to achieveand a rarity in practice.

Although levelness is primarily an aesthetic need, stability is anoperational necessity. Unless the total weight of the machine iscorrectly distributed upon the four feet, the centrifuging of anexcessively unbalanced load of clothes will cause the machine to rockintolerably on that diagonally opposite pair of feet which bears adisproportionate amount of the total weight of the machine by virtue ofone of that pair of feet being overextended a few thousandths of aninch.

Even were the machine completely, structural rigid and the floor exactlylevel and concrete hard, which rarely occurs in practice, the applianceinstallation technician would have to resort to expert, micrometeradjustment of the feet to achieve non-rocking, 100% stable, 100%coplanar adjustment of the four feet. Mere touching contact of two,diagonally opposite feet is by no means sufficient; each of the fourfeet should support the exact weight of its corner of the machine asdetermined by laboratory tests and calculations. Since appliances of thetype contemplated herein are not designed and built to have their truecenters of gravity exactly coinciding with their geometric centers, thisdoes not necessarily mean that the total weight of the machine will beevenly distributed on the four feet, rather, it means that the weightmust be distributed correctly, from the point of view of stability.

It has been proposed that machine stability can be achieved by employingtwo adjustable feet in front in combination with a single foot in thecenter rear, thus producing a tripod effect. In a rectangularly basedmachine, however, this means that half of the machine overhangs itssupports. The triangular base area defined by the three feet and belowthe machine center of gravity, in such case is but one half of therectangular area defined by four feet. Forces tending to rock themachine laterally are resisted by a base whose median width below thecenter of gravity is but one half of what it might be when four feet inproper stable adjustment are used. To

atcnt O 3,@88,593 Patented May 7, 1963 overcome this inherentdisadvantage, two interconnected rear corner feet have been proposed asa substitute for the single rear center foot; their interconnection,through linkages, cams, wedges and the like, is intended to balance theload on the rear feet by permitting one foot to recede while the otherextends an equal amount. Without any friction in the linkage, such anarrangement is but the kinetic equivalent of the tripod. With frictionadded, in an attempt to equate the system to the stability of four,precisely adjusted, independent feet, there is too much resistance topermit the feet to adjust themselves automatically, except when largeexternal forces are available. Furthermore, the long term maintenance ofa specific amount of friction, in an appliance of the class contemplatedherein, is commercially infeasible.

The preferred embodiment of the present invention is directed to aself-stabilizing mounting for appliances of the type contemplatedherein. The mounting comprises two, conventional, screw adjustable frontfeet and two, interconnected, hence oppositely moving, rear feet. Theinterconnection is hydraulic, essentially friction free and thereforeproductive of the kinetic equivalence of a tripod mounting. However,designed into the interconnection is that amount of viscous damping thatmakes the combined means, the kinetic equivalent of four, continuouslyand correctly adjusted, independent, conventional feet.

At any time, the pressure in the hydraulic system is reflective of thestatic loading on the rear feet and of the dynamic loading due to thecentrifuging of an unbalanced clothes load. The magnitude of the dynamicloading is a running product of the actual unbalance in pounds and thesquare of the instantaneous speed of the rotatably mounted clothescontainer. When this product reaches a magnitude capable of perceptiblyvibrating a given machine said loading is called the critical loadingand creates a momentary, critical pressure in the hydraulic system.Unless the accelerating forces that produce said critical pressure arechecked immediately the machines vibratory motions will becomedefinitely intolerable; accordingly, in the subject invention, theimminence of this critical pressure is employed, through a preloadedservomechanism, to deactuate the prime mover and thus to decelerate theclothes container immediately.

All of this is accomplished in the fraction of a rotation of a rapidlyaccelerating clothes container and within just that relativelyimperceptible movement of the hydraulically interconnected feet neededto maintain machine stability during the acceleration of unbalancedloads.

The servo-mechanism is made unresponsive to all but the dynamic loadingat or above the critical value. In the subject invention theservo-mechanisms deactuation of the prime mover, at the imminence of acritical loading has cooperatively associated with it a time delay meanswhereby either the machine has an opportunity to become quiescent aftera vibratory disturbance or the clothes themselves have an opportunity tore-tumble into a more favorable distribution. The hydraulicallyinterconnected feet, the viscous damping, the critical pressuresensitive servo-mechanism and the time delay means, all specific objectsof this invention would fail to achieve maximum usefulness, however, inthe absence of providing means for interposing unity coefficient offriction between the feet of the machine and the floor upon which itrests. Without adequate friction at such points of contact the machinewould oscillate laterally, long before the otherwise permissiblecritical loading value had been reached; with adequate friction not onlywould higher critical loadings be permitted but in addition, themachines rocking tendencies would be transferred from diagonal axes tofore and aft axes on either side of the machine, all to the advantage ofthe workability of the basic concept of this invention.

It is accordingly an object or" the present invention to provideadjustable foot support structure for appliances and the like that willpermit ready levelling and automatically assure optimum and maximumstability.

A further. object of the invention is to provide an adjustable and selfstabilizing foot support structure for appliances or the like, employingtwo adjacent support feet, adapted to continuously equally divide theload applied thereto and in which equilization movement of the feet isviscously damped to achieve stability A still further object of theinvention is to provide a foot structure of the character described, inwhich hydraulic interconnection with viscous damping between twoadjacent feet is employed to balance the loading on the feet.

Yet a further object of the invention is to provide, in combination withstructure of the character referred to, servoprime mover controlmechanism responsive to the dynamic loading of the viscous dampingsystem employed.

A still further object of the invention is to provide, in combinationwith structure of the character referred to, servo-prime mover controlmechanism responsive to the dynamic loading of the viscous dampingsystem employed.

A still .further object is to provide, in combination with structures ofthe character referred to, means for assuring unity coefficient offriction between feet and floor to permit attainment of the maximumadvantages from the system.

The above and other novel features of the invention will appear morefully hereinafter from the following detailed description when taken inconjunction with the accompanying drawings. It is expressly understoodthat the drawings are employed for purposes of illustration only and arenot designed as a definition of the limits of the invention, referencebeing had for this purpose to the appended claims.

In the drawings, wherein like reference characters indicate like parts:

FIGURE 1 is a perspective view from beneath of a laundry applianceshowing the feet thereof and with the cabinet broken away;

FIGURE 2 is a sectional view of one of the manually adjustable screwfeet of FIGURE 1;

FIGURE 3 is a schematic sectional view through the appliance in thecabinet;

FIGURE 4 is a vertical enlarged fragmentary sectional view taken throughthe rear feet of FIGURE 1 and hydraulic connections therebetween;

FIGURE 5 is a schematic diagram of the hydraulically actuated electriccontrol circuit;

FIGURE 6 is a circuit diagram of a washer dryer to which the hydrauliccontrol is applied;

. FIGURE 7 is a time chart for use in conjunction with FIGURE 6;

FIGURE 8 is a sectional view of a modified form of rear foot support;and

FIGURE 9 is a sectional view taken on the line 9-9 of FIGURE 8.

Referring to FIGURE 1, there is shown an appliance such as a washingmachine or washer dryer 10 having provision for support upon four feet12, 14', 16 and 18 located at the corners of the base 20. Supported onthe base and within the cabinet 21 may be a tub 30 (see FIGURE 3) havinga rotatable tumbling drum 32 therewithin. A motor 34 and two speedtransmission 36 provide the necessary two speeds of rotation of the drum32 for tumbling and centrifugal extraction respectively. Transmissionspeed change is effected by a solenoid actuated clutch 37.

The front feet 12 and 14, see FIGURE 2, are each of the screw jackadjustable type, each foot comprising a floor pad 13, a threaded shankand lock nut 17, with the shank being screw threaded into a threadedmember 19 welded or otherwise secured to the base frame 54.

The rear feet, 16 and 18, as shown in FIGURE 4 comprise piston-likeplungers 22 and 24 located in vertically disposed cylinders 40 and 42.Each cylinder has a shoulder 41, and a lower threaded portion 43extending through an aperture 4 5 in the frame 54, and is rigidlysecured in place by a nut 47. The lower end of each cylinder is providedwith a guide sleeve 49, and the plunger is provided with a sleeve 51held between spaced snap rings 53. The upper end of each cylinder isprovided with a cap or head 55, the lower end of which is swaged aroundan external flange 57 on the upper end of the cylinder body. A flexibleimpervious diaphragm having an annular flexible loop 56 disposed in theclearance between the plunger and the cylinder wall bears centrally uponthe upper end of the plunger 22, and has its rim clamped between thecylinder flange 57 and cap 55. A coil spring 59 is disposed between thesleeve 49 and the lower snap ring 53. Each of the cylinder caps isconnected by suitable fittings 61 and tubing 63 of adequate size to adetector actuator.

The detector actuator comprises a heavy base plate with rigid spacedcars 62 and 64 having aligned apertures into which the ends of thetubing 63 from each of the cylinders 40 and 42 are rigidly mounted, asby brazing or other means. Between the ears and communicating with eachof the ends of the tubes 63, are a pair of Sylphon bellows or expansiblechambers 65 and 67' spaced apart by a piston-like element 69 throughwhich extends an axial capillary port 66 intercommunicating with thebellows or chambers 65 and 67. It will be seen that the element 69 willbe moved in response to pressure differences existing in the bellows 65and 67, except for such relief as results from the intercommunicatingport 66. The element 69 and bellows form a unit, and the bellows areconnected to the ends of the element in sealed relation as by solderingor brazing or the like. The system thus far described is sealed andcompletely filled with liquid in the form of oil, or other suitableliquid, such as, for example, hydraulic brake fluid free of air orgases.

The piston member 69 is provided with an enlarged central section 68affording opposed shoulders 70 and 72. The plate 60 is provided with alaterally disposed rigid center arm 74, mounted in a plate bracket 76.The arm extends toward the piston section 68, and has on opposite sidesthereof electrical contact faces, adapted to be engaged by contactelements 73 and 75 of contact arms 78 and 80. The arms 78 and 88 aremounted on leaf springs 82 and 84 secured to the bracket, and suchsprings are suitably insulated from one another and the bracket. Thearms at their other ends are provided with piston centering projections79 and 81 adapted to contactthe opposite shoulders 70 and 72 of thecentral section 68 of the piston member 69. The projections of members79 and 81 may be of Micarta or other rigid insulating material. Meansare provided for yieldingly urging the contact arms toward one anotherand yieldingly holding the contacts 73 and 75' carried thereby againstthe contact faces of the center arm 74. Such means comprises anelongated screw 86 having its head seated in an insulating bushing 87 inarm 78. The screw extends through clearance apertures, in the center armand contact arm A coil spring 88 bears against an insulating bushing 89through which the screw extends, in the contact arm 80. The compressionof such spring is varied by a calibrating nut 90 provided on the end ofthe screw. v

The centering members 79 and 81 are spaced a distance slightly greaterby a few thousandths of an inch than the spacing between the shoulders70 and 72 on the piston element 69, and thereby yieldingly center thepiston element, by reason of the tension applied upon the contact arms78 and 80 through the calibrating spring 88. At the same time bothcontacts 73 and 75 will rest on the arm 74, when the element 69 iscentered.

Any force exerted on the piston element 69, tending to move the pistonelement axially in either direction, by reason of differential pressurein the respective bellows 65 and 67, will tend to unseat one of thecontacts 73 or 75 and open a circuit between the contact leaves 82 and84, which circuit is normally maintained closed by both contacts 73 and75 bearing against the center arm 74, under the pressure of spring 88.The contact arms tend to return the piston element to its centerposition, at such rate as is permitted by the flow of hydraulic fluidthrough the capillary port 66.

From the foregoing it will be seen that the apparatus is capable ofinstantaneously indicating pressure differences occurring in theopposite sides of the system, resulting from instantaneous changes inthe loading on the feet 16 and 18. In accordance with the setting of thecalibrating spring 88, the instant any differential pressure is createdthat exceeds the preset level, the normally closed circuit betweencontacts 73 and 75 and leaf springs 82 and 84 is instantly broken.

From a consideration of the foregoing, it will be seen that the pistonelement 69 is held in its central position under such yielding pressureas is selected by loading the calibrating spring. Flow of hydraulicliquid between cylinders 40 and 42 is permitted at a controlled ratethrough the capillary aperture 66, so that the feet 16 and 18 willequally divide the load, after the elapse of the time depending on theviscosity of the liquid and size of the aperture 66. If the unequalloading on the feet 16 and 18 is sufficient to move the piston 69 andopen one or the other of contacts 73 or 75, and such contacts are incircuit, with the motor 34 or the clutch controlling acceleration toextraction speed, starting of the motor, or extraction, will be delayeduntil the inequality in the pressure in the bellows 65 and 67 isinsufiicient to hold one or the other of the contacts 73 or 75 open,against the presetting of spring 88. Thus operation of the washingmachine is delayed until the machine approaches an even or stablefooting on all of its feet. The aperture 66 can thus be of such smallsize as to delay the final levelling over a period of minutes, and oncethe machine is level, the two sides of the system are substantiallyisolated against instantaneous flow from one side to the other, and allfour feet of the machine provide in effect a rigid support, that isstabilized.

It will thus be seen that the rear feet acting through the hydrauliccylinders and connecting conduits 63, and capillary passage 66, coactwith the front screw jack feet, to provide for transverse levelling bythe relative adjustment of the front feet 12 and 14, the port 66permitting the rear feet to adjust gradually and follow the adjustmentof the front feet. Levelling depthwise is obtained by the equal upward,or downward, adjustment of both front feet 12 and 14.

Dynamic forces, resulting from unbalanced extractor loads will createdifferential pressures within the bellows chambers 65 and 67, by reasonof the highly restricted flow through the aperture 66. The differentialpressure results from the rapidly alternating loading upon the hydraulicfeet 16 and 18, resulting from accelerating an unbalanced laundry loadfor centrifugal extraction in the drum 32 and the substantiallyinstantaneous transmission of such pressures to the bellows 65 and 67through the relatively large conduits 63. As the speed of rotation ofthe drum increases, the differential pressures created increase. Witheach complete rotation, with an unbalanced load, pressure is increasedsequentially first upon foot 16 and then on foot 18, and simul taneouslypressure is decreased on foot 18 and then on foot 16, thereby creatingtwo differential pressure impulses sequentially in opposite directionsupon the piston member 69 for each complete rotation. By presetting thecompression of spring 88, the contacts 73 and 75 may be employed to opena control circuit, should a corresponding predetermined loading beapproached during acceleration. Since either contact may open thecircuit, the control circuit is responsive to the increase in loading,due to acceleration, occurring during each half revolution of the drum.The control circuit acts to discontinue the acceleration of the drum bydeenergizing the drive motor, or by mechanically disconnecting the sameas by actuating a clutch.

Referring to FIGURE 5, wherein a suitable control circuit is shown, thecontacts 75 and 73 are in shunt with a solenoid 102, which is energizedthe instant either contact 73 or 75 opens the circuit. The solenoidactuates a diaphragm switch 103 in an air cell 104, to open the switch,and a pneumatic check valve and adjustable air bleed 106 allows thediaphragm to instantly move downwardly in response to energization ofthe solenoid, and delays the reclosing of the switch 103 for apresettable period such as 20 seconds. The circuit also comprises atimer cam operated switch 226 which determines the overall length of theextraction period, and a clutch actuating solenoid 227, which shifts thetransmission 36 to the high speed ratio to effect acceleration to theextracting speed during such period.

It will be understood that in centrifugal extracting washers of the typereferred to, the motor drives the drum 32 at tumbling speed, whicheffects a continual redistribution of the laundry load. Except forunusual laundry pieces such as, for example, pile fabric rugs, suchdistribution tends toward an even and balanced distribution. Whenacceleration takes place with a balanced distribution, objectionablevibration does not occur, and the control circuit remains closed andinactive. Should a badly balanced load occur, as acceleration takesplace, the unbalance creates ditferential pressure pulses in thedetector actuator, the magnitude of which increases with speed. On eachhalf rotation, the differential pressure created increases duringacceleration. When a differential pressure in excess of the tolerableand preset limit is reached, one or other of the contacts 73 or 75 areopened, and the circuit opened and held open by the air cell pneumaticcontrol for 20 seconds. Deceleration of the drum to tumbling speedresults, and tumbling continues until the end of the 20 second period,when redistribution will have been effected, whereupon acceleration toextraction speed is again initiated. If sufficient balance has beenestablished, full extraction speed is attained for the remainder of theextraction period. On the other hand, if severe unbalance is stillpresent, when the speed has been increased to that creating vibration inexcess of the tolerable and preset limit, either of contacts 73 or 75are opened and the 20 second deceleration and tumbling period isrepeated. Repeated acceleration up to the critical speed, of anunbalanced load, will effect centrifugal extraction, but to a lesserdegree than that obtained when the full extraction speed is initiallyattained during the extraction period. The lesser amount of waterextracted when balance does not occur, however, is not serious and isoffset by the complete elimination of intolerable vibration anddangerous forces, which would otherwise occur occasionally from a loadthat refused to distribute in a sufiiciently balanced manner.

The apparatus and circuit thus described may be applied to a washerdryer of the type disclosed in my copending application Serial No.511,186 filed May 26, 1955, to open the circuit of the extractoraccelerating motor when vibration beyond the tolerable limit occurs.Since in that arrangement acceleration occurs for a maximum of twoseconds, the time delay for reclosing the contacts 103 will need toextend only to the end of the two second period.

A washer drier circuit and time diagram for the apparatusdiagrammatically shown in FIGURE 3 and including the circuit of FIGURE 5is shown in FIGURES 6 and 7. As previously indicated, the stationary tub36 is rigidly mounted upon saddles 33, mounted on the base 20, and thetumbling drum 32 is rotated on a fixed inclined axis therewithin by themotor 34, through the two speed transmission 36, having a clutchactuated by a solenoid 227 to shift from wash speed to acceleration tothe higher extracting speed.

The circuit shown in FIGURE including contacts 73 and 75, solenoid 102and delay contacts 103 are indicated in FIGURE 6 together with the timercam switch 226 that controls extractor acceleration. Unbalanced loadsmay cause gyratory vibration, of such amplitudes as to require instanttermination of the motive power accelerating the extractor. The controlcircuit shown is applied to an apparatus wherein centrifugal extractionis effected in drum !32 at different stages of the Wash cycle.

In the circuit, 200 and 202 represent the power supply of a 220 voltsystem having a grounded neutral 204. Switches 206 and 208 are themanual start switch, usually associated with the timer, and the accessdoor switch respectively. Contacts 210, 212, 214, 216 and 218 are timercam actuated switches, for the pump and blower control solenoid 211, thedrum drive motor 34, the timer motor circuit 215, the auxiliary heater217, and the low heat heater 219 respectively. Additional timer camactuated contacts 220 and 222 for hot and warm water solenoids 221 and223, are provided. Contacts 224 and 226 are also provided forcontrolling condenser water as by solenoid valve 225, and actuation ofthe accelerating transmission clutch 37 by its actuating solenoid 227.The cam switch contacts 220, 222, 224 and 226 can only be energized whenthe tub is empty. The presence of a predetermined water level in the tub30 actuates pressure switch 228, to open the circuit to switches220--226, and close a circuit 230 to the timer motor 232 and initiatesthe washing action. Thus when the tub 30 is filled, the circuitscontrolling water supply, condensing water, and acceleration are dead.

The time diagram of FIGURE 7 shows the duration of periods in 45 secondincrements for the sequence of various operations in a complete washingand drying cycle. The wash period ends when the pump and blower switch210 is closed, thereby draining the tub. At this time, the timer switch214 is closed. Thereafter, pressure switch 228 opens circuit 230, inresponse to draining the tub and energizes circuit 233 leading tocontacts 220, 222, 224, 226. Contact 222 causes warm water to be sprayedinto the drum 32 for a period indicated at 322 while tumbling but nearthe end of the drain period. After the drain period, cam switch 226 isclosed for a 45 second period as at 323, initiating an extraction periodsince closing switch 226 energizes solenoid 227 actuating clutch 37. Anyunbalance creating dynamic forces approaching the critical loadingterminates the acceleration period by creating a diiferential pressurein the hydraulic system sufficient to move the piston 69, to instantlyopen switch contacts 73 or 75, opening the circuit for 20 seconds fordeceleration and redistribution.

At the end of the extraction period thus provided, the

contacts 226 are opened, the pump contact 210 opened,

and timer contacts 214 are opened, stopping the timer 232. Warm watercontacts 222 close. The timer is thus stopped for a fill period, untilthe water level in the tub reaches the desired level, whereupon pressureswitch 228 shifts, restoring circuit 230, to start the timer motor, andend admission of further water. Agitated rinse continues for a period oftwo timer increments indicated at 327, and during the middle of theperiod, timer contacts again close, and at the end of the rinse period,contacts 2'10 start the pump, which proceeds to drain the tub.

Thereafter, when the tub is drained, the pressure switch acts inresponse thereto, and another extraction period 325 of three incrementsduration starts, during an intermediate part of which, hot or warm sprayis introduced. Extraction continues unless interrupted by the opening ofcontacts 73 or 75 in which case deceleration and tumbling takes placefor 20 seconds after which acceleration again occurs.

Timer motor switch 214 'is'then opened and the timer 8, stops. The inletvalve is opened, to refill the tub for a further rinse. When the tub isfilled, switch 228 starts the timer, and starts a second deep rinseperiod of one increment duration, see 329. Thereafter the timer switch214 is again closed, and simultaneously, pump switch 210 is closed, todrain the tub.

Extraction follows for a period 331 of one increment in length, withacceleration to full speed, unless interrupted by the opening ofcontacts 73 and 75 in response to unbalance.

After such period, extraction is discontinued and tumbling with highheat is commenced. Thereafter, the heat rate is lowered, the auxiliaryheat period 337 terminating prior to termination of the heater period339 and the final centrifugal extraction period 341 commences during thebalance of the period 339. At the end of the extraction period, a briefperiod of tumbling is provided for without heat, after which the motor34 is cut off.

After a brief interval, the remaining stage of drying commences,contacts, 216 and 218 closing to establish high or low heat, dependingupon manual selection and actuation of switch 217. At the same time, thecontacts 212 are closed and the tumbling motor 34 starts. The condenserwater is turned on by closure of contacts 224, and the pump and blowercontacts 210 remain closed to establish air circulation through the drumand condenser. The timer contacts are opened. Upon a temperature rise,according to which of the thermostats 231, or 232 have been selected,the timer is again started through circuit 240 and the contacts 216 and218 opened to cut off further heating. After three timer increments,contacts 218 are closed, to add further heat, at which time the timer isagain cut out, if the thermostats 231 and 232 are sutficiently cool toopen the circuit 240. When the temperature again nises to closethermostat 232 or 2321, the timer starts through energization throughcircuit 240. The heat is soon cut oif by timer contacts 218, and a runout period of tumbling is assured at this point by closure of contacts214. The run out period continues, after which, the motor, blower, andcondenser are cut off. The timer motor later cuts itself off afterreturning to the initial start position.

During any of the foregoing extraction periods, should intolerableunbalance become manifest during acceleration, acceleration isimmediately terminated for 20 seconds. Following deceleration,redistribution is effected within the remainder of the 20 second delayperiod, so that upon the next acceleration, balance may be materiallyimproved. When balance is achieved, full extraction speed is attained.

In FIGURE 8, there is shown a variation of rear support feet, whichcomprises a transverse beam 400 having feet 402 and 404 at the extremeends. The appliance base 20 is provided with a trunnion bearing 406 atthe rear center thereof, from which projects a stub shaft 408, affixedto the mid point of the beam 400. Such support, at the rear of theappliance coacting with mechanically adjustable feet such as 1 2 and 14at the front serves to permit levelling as referred to hereinbefore, andprovides for proper distribution of the weight.

Viscous damping of movement between an end of the beam and the appliancebase 20 is effected by interposing a double acting cylinder and piston4'10, 412 therebetween. The cylinder 410 is aflixed to the base 20 andthe piston has a rod 414 pivotally connected to the beam as at 416. Theopposite ends of the cylinder are connected to the opposite sides of thedetector actuator of FIGURE 4 as by pipes 63' and 63', and operation isotherwise similar to that of FIGURE 4, as will readily appear.

In order to prevent the appliance from sliding on the floor in responseto the forces resulting from unbalanced loads, it is desirable toprovide means for assuring a coefiicient of friction between the feetand floor of 1 or greater. A single conical projection 440 which mayengage the floor and prevent sliding may be provided on the undersurface of each foot, or any other equally effective means may beprovided. By preventing sliding action, the unbalance forces, which canbe tolerated are increased to a maximum, and if all feet are bearingtheir proper share of the load, such force is limited only by the forcethat would cause rocking of the machine on axes extending through theright hand, or the left hand feet where they are in floor contact.

In each of the modifications set forth, the viscous damping means actsupon a pressure increase above a pre-set limit to control the drivingmeans of the rotating unbalanced extractor so as to stop theacceleration, and thereby positively prevent the further increase inmagnitude of the dynamic forces, and thus contain such forces below thecritical with precision. Whereas various spring suspensions for therotating extractor drum with damping, have heretofore been provided, inorder to permit rotation of the drum about its true center of gravity,such suspensions, in extractor drums rotating on axes out of thevertical have not been entirely satisfactory. Where no spring suspensionis provided, in a horizontal axis extractor, it has been the practice tobolt the extractor to a heavy concrete base. By mounting the applianceon feet having a coefficient of friction of 1, apparatus having nospring suspension may be made to operate, by employing the apparatusherein disclosed, during unbalanced extractor loads, at speeds up to aprecisely set maximum, so that no dynamic vibrational forces beyond thecritical can occur.

During each extraction acceleration of the program set forth in FIGURE7, the acceleration period is instantly terminated should the dynamicforces reach the preset maximum, and a twenty second delay period isallowed for deceleration and redistribution. The length of such delayperiod may be varied to suit drum diameter and weight, rigidity of thestructure and frictional forces assisting deceleration and otherfactors.

While the invention has been illustrated and described in severalmodified forms, and in connection with specific apparatus, it is to beunderstood that the invention is not limited thereto. As various changesin the construction and arrangement may be made without departing fromthe spirit of the invention, as will be apparent to those skilled in theart, reference will be had to the appended claims for a definition ofthe limits of the invention.

What is claimed is:

1. Stabilizing and leveling apparatus for laundry appliances comprisinga frame structure having four supporting feet disposed to define asubstantially quadrangular area, a centrifugal extractor mounted on saidframe including driving means therefor, means acting to continuouslydivide the static frame load carried by two adjacent feet on said frameequally between said two feet, viscous damping means associated withsaid last named means to restrict action thereof in response to dynamicunbalanced rotational forces generated by said extractor, means forvertically extending and retracting each of the other two of said fourfeet, relative to said frame, independently of each other to establishfixed positions thereof to accommodate for floor irregularity, and means1t) responsive to an increase in pressure in said viscous damping meansin response to extractor generated dynamic forces for controlling saiddriving means.

2. In a washing machine, a rectangular base frame adapted to besupported at its four corners, a vertical cylinder affixed to said frameat each of two adjacent corners thereof, a piston in each of saidcylinders having a depending floor engaging foot extending therefrom,manually vertically adjustable feet in each of the other corners, aconduit connecting said cylinders, liquid within said cylinders abovethe pistons adapted to flow from one cylinder to the other through saidconduit to balance the load on said feet, a constriction in said conduitto resist flow between said cylinders, a centrifugal extractor mountedfor rotation on said frame on an axis out of the vertical, means forsequentially accelerating said extractor, to a centrifugal extractionspeed from a tumbling speed, and subsequently decelerating saidextractor, and means responsive to differential pressure on oppositesides of said constriction for initiating operation of said deceleratingmeans.

3. In a washing machine, a rectangular base frame, adapted to besupported at its four corners, a vertical cylinder afiixed to said frameat each of two adjacent corners thereof, a piston in each of saidcylinders having a depending floor engaging foot extending therefrom,manually vertically adjustable feet in each of the other corners, a pairof aligned expansible chamber bellows having their adjacent endsconnected by a movable constricting conduit member, and their oppositeends supported in fixed spaced relation, separate conduits connectingeach bellows with a corresponding cylinder, means for yieldingly biasingsaid member against movement in either direction, in response todifferential pressures in said bellows below a preset level, acentrifugal extractor mounted for rotation on said frame on an axis outof the vertical and extending between said cylinders, means for applyingpower for accelerating said extractor to a centrifugal extraction speedfrom a tumbling speed, and means responsive to movement of said memberin response to a differential pressure in excess of said preset level todiscontinue operation of said power applying means.

References Cited in the file of this patent UNITED STATES PATENTS2,224,241 Verdier Dec. 10, 1940 2,499,494 Greer Mar. 7, 1950 2,540,750Morrison Feb. 6, 1951 2,615,499 Wallace Oct. 28, 1952 2,635,838 BransonApr. 21, 1953 2,695,147 Castricone Nov. 23, 1954 2,775,849 Ingram Jan.1, 1957 2,778,656 May Jan. 22, 1957 2,780,086 Dunlap Feb. 5, 19572,792,569 Byrkett May 14, 1957 2,807,952 Bochan et al. Oct. 1, 19572,823,975 Kirby Feb. 18, 1958 2,828,138 rBrueder Mar. 25, 1958 2,831,369Cahn Apr. 22, 1958 2,949,984 Daniels Aug. 23, 1960

1. STABILIZING AND LEVELING APPARATUS FOR LAUNDRY APPLIANCES COMPRISINGA FRAME STRUCTURE HAVING FOUR SUPPORTING FEET DISPOSED TO DEFINE ASUBSTANTIALLY QUADRANGULAR AREA, A CENTRIFUGAL EXTRACTOR MOUNTED ON SAIDFRAME INCLUDING DRIVING MEANS THEREFOR, MEANS ACTING TO CONTINUOUSLYDIVIDE THE STATIC FRAME LOAD CARRIED BY TWO ADJACENT FEET ON SAID FRAMEEQUALLY BETWEEN SAID TWO FEET, VISCOUS DAMPING MEANS ASSOCIATED WITHSAID LAST NAMED MEANS TO RESTRICT ACTION THEREOF IN RESPONSE TO DYNAMICUNBALANCED ROTATIONAL FORCES GENERATED BY SAID EXTRACTOR, MEANS FORVERTICALLY EXTENDING AND RETRACTING EACH OF THE OTHER TWO OF SAID FOURFEET, RELATIVE TO SAID FRAME, INDEPENDENTLY OF EACH OTHER TO ESTABLISHFIXED POSITIONS THEREOF TO ACCOMMODATE FOR FLOOR IRREGULARITY, AND MEANSRESPONSIVE TO AN INCREASE IN PRESSURE IN SAID VISCOUS